def shrink(cur_workers, shrink_ratio, pool):
ec2 = boto3.resource('ec2')
#don't do anything if only one worker
if cur_workers == 1:
return True
#number of workers to remove
target_workers = cur_workers - ceil(cur_workers / shrink_ratio)
#remove required number of instances from worker pool
for i in range(target_workers):
removed_inst = remove_one_ec2(pool)
removed_item = removed_inst[0]
remove_from_elb(removed_item)
sleep(5)
ec2.instances.filter(InstanceIds=[removed_item]).terminate()
try:
pool.remove(removed_inst)
except Exception:
pass
message = "removed instance " + removed_item
print(message)
#sleep(5)
message = "removed " + str(target_workers) + " workers"
print(message, flush=True)
return True
def ec2_shrink():
# create connection to ec2
ec2 = boto3.resource('ec2')
instances = get_workpool()
removed_inst = remove_one_ec2(instances)
if removed_inst == False:
removed_item = ''
else:
removed_item = removed_inst[0]
if len(instances) == 0:
flash("There is no Instance Available")
return redirect(url_for('ec2_list'))
if removed_item != '':
remove_from_elb(removed_item)
sleep(5)
ec2.instances.filter(InstanceIds=[removed_item]).terminate()
message = "removed instance " + removed_item
else:
message = "Can't Shrink Anymore: Only One Instance Left in the Load Balancer"
flash(message)
return redirect(url_for('ec2_list'))
def ec2_destroy(id):
# create connection to ec2
ec2 = boto3.resource('ec2')
remove_from_elb(id)
ec2.instances.filter(InstanceIds=[id]).terminate()
return redirect(url_for('ec2_list'))
def ec2_termination():
# create connection to ec2
ec2 = boto3.resource('ec2')
instances = get_workpool()
#remove instance from the load balancer and terminate
for inst in instances:
remove_from_elb(inst[0])
ec2.instances.filter(InstanceIds=[inst[0]]).terminate()
flash("All workers have been terminated")
return redirect(url_for('ec2_list'))
def ec2_deregister(id):
remove_from_elb(id)
return redirect(url_for('ec2_list'))